Reliability Upgrading of Long Period Component of Strong Ground Accelerograms and their Applications to Large Scale Structures

将SMAC加速度记录的反应谱与其它类型的地震仪的反应谱进行比较，发现在5秒左右的周期范围内，SMAC加速度记录的反应谱值比其它类型的地震仪的反应谱值大。由品川的SMAC加速度记录确定的反应谱与SAMTAC的加速度反应谱进行了比较。为了研究SMAC加速度计在较长周期范围内的记录特性，将SMAC加速度计与其它地震计和位移计在振动台上进行了振动试验。在SMAC记录中会引起漂移和起伏，这些不需要的分量通常具有所谓的1/f谱形状。记录笔在低频分量周围移动30秒也具有1/笔的移位和漂移是由连接该笔的链路的缺陷之间的耦合引起的。钟摆和记录笔的运动以及笔和纸之间的摩擦。这支笔由针头推动，由弹簧圈拉动。但是，当笔和纸之间的摩擦力大于弹簧的刚度时，笔不会被弹簧拉动。因此，笔被留下，记录被移动。因此，必须从每个记录中消除记录漂移。在假设相位不变的情况下，从原始谱中减去噪声分量谱，将所提出的校正方法应用于多条SMAC记录，并将结果与位移型强震地震计的记录进行了比较。对加速度反应谱进行了比较，结果令人满意。

When response spectra determined from SMAC accelerograms are compared with that from other kind of seismographs, the former gives larger value for the period range over about 5 second than the latter. The response spectrum determined from a SMAC accelerogram recorded at Shinagawa is compared with the acceleration response spectrum from SAMTAC which is a digital type accelerograph. While both spcetra almost coincide for the shorter period range, the response spectrum for SMAC record quite differs from that for SAMTAC record.In order to investigate the recording characteristics of longer period range of SMAC accelerograph, a SMAC accelerograph was shaken on a shaking table with other seismometers and displacement meters. The shift and fluctuation are induced in a SMAC record and these undesirable components have commonly so-called 1/f spectral shape.When a SMAC was driven by the Hachinohe record, the recording pen was shifted at 30 second around low frequency component has also 1/f spectral shape and it is caused by the shift of the pen.The shift and drift of the pen is caused by a coupling between a defect of the link connecting the motion of the pendulum and recording pen and a friction between pen and paper. The pen is pushed by needle and pulled by a spring coil. However, when the friction between the pen and paper is greater than the stiffness of the spring, the pen is not pulled by the spring. Consequently the pen is left behind and the record is shifted. Therefore, the drift of record must be removerd from each record. A spectrum of noise component was subtracted from the original spectrum under the assumption that the phase remains unchanged.The proposed correction method was applied to a number fo SMAC records and results were compared with records obtained by strong motion seismometer of displacement type. Comparison was done on the acceleration response spectrum and the result was satisfactory.